1. Field of the Invention
The present invention relates to a braking device for automotive vehicles which is designed to apply a braking force to the road wheels of tile vehicle in a predetermined relationship with a depression force applied to a brake pedal.
2. Discussion of the Prior Art
In Japanese Patent Laid-open Publication No. 58-188746, there has been proposed a braking device of the type which includes a pressure sensor for detecting a depression Force applied to a brake pedal and a speed sensor for detecting a rotational speed of a road wheel, wherein a brake booster assembled with a master cylinder is operated in accordance with the detected depression force of the brake pedal and a deceleration of the vehicle calculated on a basis of the detected rotational speed of the road wheel. The braking device is effective to cause a desired deceleration of the vehicle in accordance with the depression force of the brake pedal even if the dynamic frictional coefficient of lining pads of the applied disc brake assembly decreases due to an error in manufacturing process of the brake assembly or rise of the temperature of the brake assembly.
In operation of the braking device, however, the deceleration of the vehicle is calculated on a basis of the detected rotational speed of the road wheel. For this reason, if the vehicle passes over a projection or recess on the travel road in braking operation, the operation of the brake booster will be controlled to decrease the braking force applied to the road wheel. As a result, the braking force becomes insufficient after the vehicle has passed over the projection or recess on the travel road.